I am facing Laravel collective/html class form not found error

I did all the step at cmd clear cache,route,update,optimize artisan but nothing worked.any there suggestion for it? this is .json file

{ "name": "laravel/laravel", "description": "The Laravel Framework.", "keywords": ["framework", "laravel"], "license": "MIT", "type": "project", "require": { "php": ">=5.5.9", "laravel/framework": "5.2.*", "laravelcollective/html" : "^5.2" },

this is my view...config/app is also ok

    @extends('layouts.app')

@section('content')
        <!-- <div class="container"> -->
            <h1>Create Post</h1>
            <!-- <div class="content"> -->
                {!! Form::open() !!}
                    <input type="text" name="content">
                    <input type="submit" name="submit">
                </form>

            <!-- </div>
        </div> -->
@endsection

via Chebli Mohamed